U.S. Pat. No. 3,799,758 issued to John E. Franz on Mar. 26, 1974 describes the preparation and herbicidal utility of N-phosphonomethylglycine and its esters, amides, and salts.
U.S. Pat. No. 4,120,689 issued to Gerard A. Dutra on Oct. 17, 1978 describes alkyl[di-(benzyl) or di-(aryl)] esters of N-phosphonomethylglycine which are produced by the reaction of a dibenzyl or diaryl phosphite with an N-methylene alkyl glycinate trimer. These esters and the hydrolysis products thereof containing at least one benzyloxy or aryloxy group bonded to phosphorous are compounds disclosed as having the formula ##STR1## wherein
R is a member of the group consisting of phenyl, benzyl, naphthyl, biphenyl, and phenyl, benzyl or naphthyl groups substituted with from 1 to 3 groups selected from the class consisting of hydroxyl, lower alkyl, lower alkoxy, lower alkylthio, trifluoromethyl, carbo (lower alkoxy), nitro or halo;
R.sub.1 is hydrogen or an R group; and
R.sub.2 is a lower alkyl group or hydrogen, and the strong acid salts of the compounds wherein neither R.sub.1 or R.sub.2 is H. These compounds are useful as postemergent herbicides.
Several N-protected thionoglycinate esters are described in the chemical literature. Specifically, the sulfonamide-protected derivative represented by the formula ##STR2## has been demonstrated by W. Reid and W. Von der Emden [Liebigs Ann. Chem., 642, 128-33 (1960)]. Carboxamide protecting groups have also been frequently employed to produce derivatives represented by the formula ##STR3## Specific examples include those wherein R is phenyl and R.sub.1 is methyl [G. Lowe and A. Williams, Biochem. J., 96, 189-93 (1965); wherein R is benzyloxy and R.sub.1 is ethyl [W. Reid and W. Emden, ibid]; and wherein R is benzyl or phenethyl and R.sub.1 is methyl [P. R. Carey et al, Biochemistry, 21, 3102-8 (1982)].
However, there are no examples in the chemical literature of fully deprotected thionoglycinate esters or simple N-alkyl derivatives thereof which are stable at room temperature and are represented by the formula ##STR4## wherein R.sub.1 is hydrogen or an alkyl group, and R.sub.2 is lower alkyl.
It will be apparent from a study of the above patents and publications that none of them disclose or suggest thionoglycinate esters containing an N-[(diaryloxyphosphinyl)methyl]group. In fact, one would anticipate that such compounds could not be prepared in light of the known facile reaction between thiono ester groups and primary or secondary amines [R. Rapp, Canad. J. Chem., 46, 2255-61 (1968); M. K. Kaloustian et al, J. Org. Chem., 44, 666-8 (1979); M. K. Kaloustian and R. B. Nader, J. Org. Chem., 46, 5052-54, (1981)], as well as amino acids, [P. Campbell and B. A. Lapinskas, J. Am. Chem. Soc., 99, 5378-82 (1977)] at room temperature.